To access the coronary (or other) arteries for a variety of purposes including dilation of stenoses, an interventional cardiologist would first introducer a guide wire through an arterial access needle puncture at the groin, and then an introducer sheath with dilator would be advanced over the guide wire and into the lumen of the femoral artery. The dilator would then be removed and a guiding catheter would be advanced through the sheath and over the guide wire until the guiding catheter's distal end would be situated in the ostium of a coronary artery. An artery opening catheter (such as a balloon angioplasty catheter or atherectomy catheter) would then be advanced through the guiding catheter, and an angioplasty or atherectomy procedure would be performed to open an arterial stenosis. In recent practice, intra-arterial stents are placed at the site of the opened stenosis by means of a stent delivery catheter. These stent delivery catheters require a fairly large diameter guiding catheter; typically 9 or 10 French size. Since the outer diameter of the sheath through which the guiding catheter is inserted is typically 2 French sizes larger then the size of the guiding catheter, a fairly large diameter hole must be made through the wall of the femoral artery. These larger size holes often lead to excessive bleeding at the groin after the sheath is removed. Furthermore, the radial artery from the arm could be used for accessing coronary arteries, but it is even more sensitive to the diameter of catheters passing through it as compared to the femoral artery at the groin.
To perform an artery opening procedure with a guiding catheter, it is also necessary to attach a Tuohy-Borst "Y" adaptor onto the guiding catheter's proximal end. The introducer sheath and Tuohy-Borst "Y" adaptor are each components that require additional time for the interventional cardiologist to properly place, and they add to the cost of performing artery opening procedures.